EP0604591A1 - Systeme analyseur de signal spectral. - Google Patents

Systeme analyseur de signal spectral.

Info

Publication number
EP0604591A1
EP0604591A1 EP92921393A EP92921393A EP0604591A1 EP 0604591 A1 EP0604591 A1 EP 0604591A1 EP 92921393 A EP92921393 A EP 92921393A EP 92921393 A EP92921393 A EP 92921393A EP 0604591 A1 EP0604591 A1 EP 0604591A1
Authority
EP
European Patent Office
Prior art keywords
wave form
temperature
phase
current
dominant frequency
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP92921393A
Other languages
German (de)
English (en)
Other versions
EP0604591B1 (fr
Inventor
Promit Das
Terrance Roger Kinney
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honeywell International Inc
Original Assignee
AlliedSignal Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AlliedSignal Inc filed Critical AlliedSignal Inc
Publication of EP0604591A1 publication Critical patent/EP0604591A1/fr
Application granted granted Critical
Publication of EP0604591B1 publication Critical patent/EP0604591B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00

Definitions

  • This invention relates to a processing system f analyzing a spectral signal generated by exposing a birefringent sensor to a temperature to create a current wave form which is matched with a reference wave form to inform an operator of the temperature experienced by the birefringent sensor.
  • a fiber optic sensor to meet th operational temperature requirements of an aircraft has resulted in the evaluation of many materials to meet the operational temperature and pressure conditions experienced during the operation of an aircraft.
  • One suc material for use as a temperature sensor is a fluorescent material.
  • the luminescent decay time for a fluorescent material can be used to generate a signal corresponding t the temperature in a hostile environment such as created in the combustion chamber of a turbine engine.
  • U.S. Patent 5,036,194 discloses a cable for the transmission o such a signal to a processor.
  • the accuracy of the sensed temperature which is directly dependent on the processing of the signal from the sensors requires special decoding techniques, such as disclosed in U.S. Patent 5,004,910. This type of sensor functions in an adequate manner when the temperature required to be sensed is in the range of from 100 to 400°C. However the temperature in a combustion chamber of a turbine engine can reach 1100°C.
  • U.S. Patents 4,140,393 and 4,928,005 It is suggested in U.S. Patents 4,140,393 and 4,928,005 that temperature dependent birefringent sensor materials could be used as a sensor material to evaluate temperature changes.
  • U.S. Patent 4,928,005 indicates tha a temperature between -100 to +300°C can be measured by analyzing deviations of modulated signals generated by light passing through coupling points. This induced modification created by light passing through coupling points along the communication cable may be adequate for some applications where dynamic forces are not applied to the cable, however in an airframe the introduction of G forces may eventually cause the cable to rupture or crack which would adversely effect the signal transmission.
  • Copending U.S. Patent Application CRD 2760 discloses a sensor system using a the birefringent properties of crystals of lanthanum beryllate (BEL) to measure temperature and stress in an environment having a temperature range of from -200 to +1500°C.
  • BEL lanthanum beryllate
  • an optic excitation signal generated by a light emitting diode in an opto-electronic interface is transmitted to a remote detector by a first optical fiber conductor.
  • the optic excitation signal is then spectrally modulated by the sensor as a function of the temperature and uniaxial stress in the sensor's active element.
  • the modulation of the signal resembles a fringe pattern which is caused by constructive and destructive interference of the optic excitation signal.
  • the spectrally modulated optic signal is transmitted from the sensor to the opto-electronic interface by a second optical fiber conductor.
  • the opto-electronic interface initially spectrally disperses the optic signal and then images the dispersed optic signal onto a charge couple device (CCD) array to produce an electrical signal output.
  • CCD charge couple device
  • the signal spectral output of the CCD array whose amplitude with respect to time relates to the optic intensity with respect to wavelength.
  • the signal output is convert from an analog to a digital signal to establish a prefac wave form when the birefringent sensor is exposed to kno temperature.
  • a Fast Fourier Transformation is performed on the preface wave form to determine its dominant frequency.
  • the reference wave form and its dominant frequency are stored in the memory of a digital signal processor. Thereafter the birefringent sensor is expose to an unknown temperature to develop a current spectral output signal.
  • the current spectral output signal is converted from an analog to a digital signal to establis a current wave form.
  • the phase and dominant frequency relationship between the current wave form and the reference wave form are is obtained by combination of cross correlation and thereafter a Fast Fourier Transformation.
  • the current dominant frequency is compared with the reference dominant frequency to determine a temperature range.
  • a signal representing the current temperature of the birefringent sensor is stored in the memory of the digital signal processor. Periodically the memory is read by a host computer and displayed on a screen to continually observe changes in temperature experienced by the birefringent sensor.
  • Figure 1 is a schematic illustration of an spectrometer system which uses a birefringent sensor to obtain a spectral signal supplied to an array from which a current temperature of a sensor is obtained by analyzin changes in a fringe pattern according to a process disclosed by the current invention
  • Figure 2 is a graph illustrating a reference wav form and a current wave form generated from a spectral output signal from the array of Figure 1;
  • Figure 3 is a graph illustrating the phase shift with respect to temperature for the birefringent sensor o Figure 1;
  • Figure 4 is a graph illustrating cross-correlation of the phase difference between the reference wave form and a current wave form
  • Figure 5 is a graph illustrating a dominant frequency and phase for the cross-correlation of the reference and current wave form of Figure 2.
  • Figure 1 illustrates an spectrometer system 100 wherein excitation broad band spectrum light from a light emitting diode 101 having a bandwidth of 50nm and spectral content as illustrated by curve 102.
  • Light is communicated by fiber optic cable 112 to a sensor 109 ma up of a first polarizer 104, a birefringent element 108 and a second polarizer 110.
  • the first polarizer 104 orients the polarization vector of the light before bein presented to a birefringent element 108.
  • the birefringe element 108 which is made of a lanthanum beryllate cryst orientated with its optic axis ideally at a 45° angle relative to the first 104 and second 110 polarizing elements, is compatible with the operational temperature of the desired use for this spectrometer system 100. Th optic excitation of the polarized light is spectrally modulated by the birefringent element 108 as a function induced temperature and stress in the environment in whi the birefringent element 108 is located.
  • the modulation of the light by the birefringent element 108 which resembles a fringe pattern such as illustrated by curve 114, is caused by the constructive and destructive interference of the optic excitation of the light emittin diode 101 by a signal from the timing and control logic controller 144 when passed through a second polarizer 110 before being communicated by fiber optic cable 118 to a prism 120 which disperses and focuses the modulated light onto an array of photo-detectors 116.
  • the array of photo-detectors or a charge couple device (CCD) 116 responds to the intensity of the dispersed light to produce a spectral output signal which is communicated to an analyzer system 124.
  • the spectral output signal from array 116 is communicated to an 8-BIT analog to digital converter 122 where the output spectral signal is converted from an analog to a digital signal and communicated to a digital signal processor 125 to generate a reference wave form 12 as shown in Figure 3, by exposing the birefringent elemen 108 to a known temperature (20°C) .
  • the dominant frequenc d(f) of the reference wave form 126 is obtained in the digital signal processor 125 performing a Fourier Transformation upon the reference wave form 126 and then 5 referencing the maximum amplitude in the frequency spectrum. This transformation is consistent with the following digital Fourier Transformation formula:
  • k is a selected entry point or index of the resultant of the Fourier Transformation of the spectral scan; N is number of sample points of window "w" such as shown in Figure 3; and n is the summation index, from 0 to N-l.
  • the reference wave form 126 and its dominant frequency d(f) are is stored in the memory 131 associated with the digital signal processor 125.
  • both phase and frequency information obtained from a current fringe pattern produced when the birefringent element 108 is exposed to an unknown temperature are compared with stored reference phase and dominant frequency information to predict the unknown temperature in the following manner.
  • Birefringent element 108 is exposed to an unknown temperature and the light from the light emitting diode after passing through polarizer 110 is communicated to detector array 116.
  • the output spectral signal from array 116 is converted an fr an analog to a digital signal by the 8-BIT converter* 122 and communicated to the digital signal processor 125 to establish a current wave form 128 as shown in Figure 2.
  • N is number of sample points
  • n is the summation index, from 0 to N-l
  • x ( ) is the signal for the reference wave form
  • y ( ) is the signal for the current wave form, phase and frequency relationship illustrated by curve 13 in Figure 4 is obtained.
  • a Fast Fourier Transformation is performed on the cross correlating cur 1 0 to obtain the dominant frequency illustrated by curv 132 in Figure 5 for the current phase and frequency relationship.
  • the dominant frequency for the phase and frequency relationship for the current wave form is compared with the dominant frequency of the reference wa form previously stored in memory 131 of the digital sign processor 125 to determine a temperature range for the current dominant frequency 132.
  • the temperature range and dominant frequency curve 132 are matched with a reference information or table in the memory 131 of digital signal processor 125 to determine the current temperature of th birefringent element 108.
  • the current temperature as determined in the digital signal processor 125 is communicating to an operational control or host computer
  • the current temperature is displayed on a scre 142 to visually inform an operator of the operational conditions experienced by the birefringent element 108.
  • the digital signal processor 125 and 8-BIT convertor 122 are all controlled by a common timing and logic control 144 that receives an input from the main or host computer 140.
  • the digital signal processor 125 receives an input operational signal to read the current wave form 128 from the photodetector array 116.
  • the timing of the processing of a current wave form from the photodetector array 116 may vary from submilli-seconds to several milli-seconds depending on the location and function observed by birefringent element 108 to keep the main or host computer 140 informed of the changes in temperature experienced by the birefringent element 108.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Radiation Pyrometers (AREA)

Abstract

Procédé d'analyse d'un signal spectral généré par un élément biréfringent et transmis à un réseau. Un signal spectral de sortie émanant du réseau est converti en un signal numérique à partir de son état analogique afin d'établir une forme d'onde de référence ayant une fréquence dominante, après exposition de l'élément biréfringent à une température connue. Ensuite, une forme d'onde effective est générée à partir du signal spectral de sortie émanant du réseau. On obtient une relation de phase et de fréquence par corrélation croisée de la forme d'onde effective et de la forme d'onde de référence. La fréquence dominante de la relation de phase et de fréquence est obtenue par transformation rapide de Fourier. Ensuite, on compare la fréquence dominante de la relation de phase et de fréquence de la forme d'onde effective à la fréquence dominante de la forme d'onde de référence afin de déterminer une plage de températures. On adapte la plage de températures ainsi que la phase et la fréquence dominante de la forme d'onde effective à un programme de référence stocké dans la mémoire d'un processeur de signal numérique afin de prédire la température effective à laquelle est soumis l'élément biréfringent. Cette température prédite est affichée sur un écran afin d'informer un utilisateur des conditions opérationnelles effectives auxquelles est soumis l'élément biréfringent.
EP92921393A 1991-09-19 1992-09-16 Procede pour analyseur un signal spectral Expired - Lifetime EP0604591B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US762837 1991-09-19
US07/762,837 US5317524A (en) 1991-09-19 1991-09-19 Spectral signal analyzer system
PCT/US1992/007846 WO1993006445A1 (fr) 1991-09-19 1992-09-16 Systeme analyseur de signal spectral

Publications (2)

Publication Number Publication Date
EP0604591A1 true EP0604591A1 (fr) 1994-07-06
EP0604591B1 EP0604591B1 (fr) 1996-11-13

Family

ID=25066147

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92921393A Expired - Lifetime EP0604591B1 (fr) 1991-09-19 1992-09-16 Procede pour analyseur un signal spectral

Country Status (6)

Country Link
US (1) US5317524A (fr)
EP (1) EP0604591B1 (fr)
JP (1) JPH07502114A (fr)
CA (1) CA2116858A1 (fr)
DE (1) DE69215233T2 (fr)
WO (1) WO1993006445A1 (fr)

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Publication number Priority date Publication date Assignee Title
US5633811A (en) * 1994-12-09 1997-05-27 Computational Systems, Inc. Hand held data collector and analyzer system
US5825492A (en) * 1996-04-26 1998-10-20 Jaton Systems Incorporated Method and apparatus for measuring retardation and birefringence
US5734577A (en) * 1996-03-11 1998-03-31 Lucent Technologies Inc. Adaptive IIR multitone detector
US6275781B1 (en) 1997-07-29 2001-08-14 Skf Condition Monitoring, Inc. Vibration data processor and processing method
US6845326B1 (en) 1999-11-08 2005-01-18 Ndsu Research Foundation Optical sensor for analyzing a stream of an agricultural product to determine its constituents
US6624888B2 (en) 2000-01-12 2003-09-23 North Dakota State University On-the-go sugar sensor for determining sugar content during harvesting
EP1315219B1 (fr) * 2001-06-20 2010-09-01 Dai Nippon Printing Co., Ltd. Materiau d'emballage de batterie
US6618142B1 (en) * 2001-06-26 2003-09-09 The United States Of America As Represented By The Secretary Of The Navy Compact birefringent spectrometer
US11906368B2 (en) * 2020-06-03 2024-02-20 Fluke Corporation Temperature measurement system and method using optical signal transmission through an optical interferometer
TW202207558A (zh) * 2020-06-03 2022-02-16 美商富克有限公司 使用共振器差分技術之光子裝置

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US3700801A (en) * 1966-10-03 1972-10-24 Trw Inc Image analysis and correlation system and method
US3573446A (en) * 1967-06-06 1971-04-06 Univ Iowa State Res Found Inc Real-time digital spectrum analyzer utilizing the fast fourier transform
US4139897A (en) * 1977-03-18 1979-02-13 The United States Of America As Represented By The Secretary Of The Navy Fast two dimensional fourier transform device
US4329058A (en) * 1979-01-22 1982-05-11 Rockwell International Corporation Method and apparatus for a Fabry-Perot multiple beam fringe sensor
JPS6128070U (ja) * 1984-07-26 1986-02-19 パイオニア株式会社 デイジタル周波数位相比較器
US4901244A (en) * 1985-01-25 1990-02-13 Szeto Lai Wan M Apparatus for, and method of, analyzing signals
FR2595820B1 (fr) * 1986-03-13 1990-01-05 Bertin & Cie Dispositif a fibres optiques pour la detection a distance d'une grandeur physique, en particulier de la temperature
JPH01158326A (ja) * 1987-09-11 1989-06-21 Toshiba Corp 温度測定装置
FR2626367B1 (fr) * 1988-01-25 1990-05-11 Thomson Csf Capteur de temperature multipoints a fibre optique
US4857726A (en) * 1988-02-29 1989-08-15 Allied-Signal Inc. Method to decode relative spectral data
US5004910A (en) * 1989-08-04 1991-04-02 Allied-Signal Inc. Method of decoding encoded relative spectral data
JP3095231B2 (ja) * 1990-09-20 2000-10-03 浜松ホトニクス株式会社 偏光測定装置及び位相板測定装置

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Also Published As

Publication number Publication date
CA2116858A1 (fr) 1993-04-01
DE69215233D1 (de) 1996-12-19
DE69215233T2 (de) 1997-03-27
WO1993006445A1 (fr) 1993-04-01
EP0604591B1 (fr) 1996-11-13
JPH07502114A (ja) 1995-03-02
US5317524A (en) 1994-05-31

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